This invention relates to a flexible control system and in particular, to an automatic working system including a plurality of machine units each implementing an individual role. For example, machine units include a welding robot and at least one positioner. The positioner serves to orientate a workpiece for the convenience of welding by the welding robot.
In a conventional automatic working system, the welding robot and positioners are controlled by a single controller, as disclosed in U.S. Pat. No. 4,042,161, and its control scheme is to operate a plurality of machine units simultaneously or one at a time in turn.
The above-mentioned prior art does not intend to control separately machine units which constitute an automatic working system, and cannot direct machine units to operate individually.